Braking device for carriage type drafting machines

ABSTRACT

A braking device for a drafting machine carriage which is supported for movement on a trackway, together with an associated drafting head assembly, wherein a brake member is normally spring urged towards a brake applying position with respect to the trackway, and in which an easily accessible actuator lever, provided with a camming surface operatively associated with the brake member, is manually movable respectively to a plurality of brake operating dwell positions including a &#39;&#39;&#39;&#39;brake on&#39;&#39;&#39;&#39; normal position in which the lever is positioned ajdacent the drafting head assembly and from which posiiton the lever is movable in one direction to momentarily release the brake element, and in an opposite direction to successive salient positions, the first providing a permanent &#39;&#39;&#39;&#39;brake off&#39;&#39;&#39;&#39; position, and the next again providing a permanent &#39;&#39;&#39;&#39;brake on&#39;&#39;&#39;&#39; position in which the brake actuating lever extends in close proximity along the trackway so as to protect the actuating lever and hold the carriage against movement during shipping.

United States Patent 11 1 Harris et al.

[111 3,760,907 [451 Sept. 25, 1973 1 BRAKING DEVICE FOR CARRIAGE TYPE DRAFTING MACHINES [76] Inventors: Harlan N. Harris, 9981 Pali Ave., Tujunga, Calif. 91042; Edward T. Harris, 1401 Nolden, Los Angeles, Calif. 90042 22 Filed: Apr. 22, 1971 21 Appl. No.: 136,498

Primary Examiner-Richard E. Aegerter Att0rney-Robert M. McManigal [5 7 ABSTRACT A braking device for a drafting machine carriage which is supported for movement on a trackway, together with an associated drafting head assembly, wherein a brake member is normally spring urged towards a brake applying position with respect to the trackway, and in which an easily accessible actuator lever, provided with a camming surface operatively associated with the brake member, is manually movable respectively to a plurality of brake operating dwell positions including a brake on normal position in which the lever is positioned ajdacent the drafting head assembly and from which posiiton the lever is movable in one direction to momentarily release the brake element, and in an opposite direction to successive salient positions, the first providing a permanent brake off position, and the next again providing a permanent brake on" position in which the brake actuating lever extends in close proximity along the trackway so as to protect the actuating lever and hold the carriage against movement during shipping.

PATENTEDSEPZSIQN HA 24AM M HAee/s 60144460 I HA ee/s INVENTORS.

Af/U/WQV far A BRAKING DEVICE FOR CARRIAGE TYPE DRAFTING MACHINES BACKGROUND OF THE INVENTION The present invention relates generally to the field of 5 drafting machines.

Heretofore, track-type drafting machines, and particularly those of the two-track type, have become a very important tool in the industry. Usually these machines comprise a horizontal track which is attached to the upper horizontal edge of a drafting table or board so as to extend parallel thereto, a horizontal moving carriage supported by means of wheels or rollers, a vertical track attached to the horizontal carriage so as to extend perpendicular to the horizontal track. The vertical track is equipped with a vertical carriage which is supported by means of wheels or rollers, and a drafting head assembly which is carried by the vertical carriage and is equipped with various devices such as a protractor head equipped with scales.

The usefulness of drafting machines embodying the above basic conventional arrangement has been greatly extended as well as the ability to more efficiently per? form the various operations by the utilization of braking devices whereby the vertical and horizontal carriages may be permitted to freely move along their associated tracks, or by which they may be releasably secured against movement at any desired position along the track. It is with the braking mechanism that the present invention is particularly concerned, and in particular the braking mechanism for the vertical carriage.

Usually the heretofore known drafting machine structures have utilized a braking arrangement in which a brake shoe is supported on the carriage for movement into a braking and non-braking position with respect to the associated trackway. The brake shoe is urged usually by a spring into a non-braking position, and a hand actuator with a camming surface provided to motivate the brake shoe into the braking position. A braking mechanism which is representative of the previously known arrangements is that disclosed in the Kuhlman US Pat. No. 3,489,250 which provides a braking mechanism arranged to effect either a continuous braking initiated by a momentary manual force or a braking action that lasts only as long as the externally applied manual force.

While the arrangement in this patent was in some respects an improvement over prior existing arrangements, it was more or less cumbersome in that it embodied more than one actuator and relied upon the application of a manually applied force in order to place the brake in a braking position.

The present invention proposes to solve the inherent disadvantages of the prior known devices by the provision of a single actuating lever which is manually operable to a plurality of dwell positions to efiect a plurality of braking and non-braking functions in order to comply with different operating requirements as become necessary for a variety of different conditions.

SUMMARY OF THE INVENTION The present invention relates generally to drafting machines of the carriage type, in which a carriage is movably supported on a trackway, and is more particularly concerned with an improved braking device carried by the carriage and arranged for movement into braking and non-braking relation with the associated trackway.

Having in mind the inherent disadvantages of the prior known braking structures as provided in drafting machines of the carriage type, it is one object of the present invention to provide a unique braking device on a track supported movable carriage in which a braking element is spring-loaded so as to normally be motivated into a braking position, and which is manually operable into a non-braking position.

A further object is to provide in a braking device for a drafting machine, a single actuator lever which is located in an easily accessible position adjacent the drafting head assembly.

A further object of the invention resides in the provision of a single brake actuating lever having a head portion pivoted on the carriage for swinging movement to a plurality of salient dwell positions corresponding to desired brake operating positions, and in which the head portion has camming relation with a follower element connected with the braking element.

A still further object is to provide in a braking device of the character described, a single actuating lever which can be set in a normal braking position, and yet can be manually moved from such normal position in order to temporarily release the brake, and upon release of the actuator lever, the lever will return to the normal braking position. v

I Yet another object is to provide a brake actuating lever which is manually swingable into a dwell position so as to extend generally along the trackway, the lever at this position placing the brake in its braking position so as to hold the carriage against movement along the track and place the actuator lever in a protected position-where it will be less apt to be damaged when the trackway and mounted carriage are disassembled and shipped.

Further objects and advantages of the invention will be brought out in the following part of the specification, wherein detailed description is for the purpose of fully disclosing a preferred embodiment of the invention without placing limitations thereon.

. BRIEF DESCRIPTION OF THE DRAWINGS Referring to the accompanying drawings, which are for illustrative purposes only:

FIG. 1 is a fragmentary top plan view of a carriage and associated trackway embodying a braking device according to the present invention, certain portions being broken away to show the operative relationship of certain of the essential parts;

FIG. 2 is an enlarged transverse fragmentary sectional view, taken substantially on line 2-2 of FIG. 1 to show the roller mounting of the carriage on the trackway, and operative relationship of the braking means with the trackway; and FIG. 3 is an enlarged fragmentary plan view showing the camming relationship between the head end of the actuating lever and a cam follower element connected with the brake element.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring more specifically to the drawings, for illus' trative purposes, the invention is shown in FIG. 1 as embodying a carriage as generally indicated at 10 supported for guided movement along trackways 11a and 11b formed in the opposite sides of an elongate extruded beam member 12 which provides a protective housing over the carriage during its movement along the trackways.

The carriage includes a main frame plate 13 of generally rectangular configuration, and upon which guide rollers 14 are mounted at the plate ends by suitable conventional means so as to permit the peripheries of the rollers at the opposite sides of the frame plate to extend into a guiding groove 15 in each case formed in the associated trackway. As best shown in FIG. 2, the rollers thus support the main frame plate 13 in a subtending position below the beam member 12 so that a plate frame side extension 13a may laterally extend beyond the beam member 12 and provide a support for an associated hinge joint connector 16 of conventional construction and by means of which a drafting head assembly as generally indicated at 17 may be removably connected with the carriage. As shown, the head assembly in this case includes a conventional control handle 18 and protractor dial 19 of conventionally known construction.

The braking mechanism of the present invention will now be described, and as shown in FIG. 1 comprises an elongate brake member 20 which is positioned intermediate the ends of the main frame plate 13 on the upper side of the frame plate and is supported at one end for pivotal swinging movement by means of a shouldered screw pivot 21. The brake member 20 extends in a direction generally parallel to the longitudinal axis of the frame plate 13, and at its outermost end has a laterally deflected end portion 22 which is operatively connected with one end of a compression spring 23, the other end of this spring being connected to a spring retainer 24 mounted on the plate 13 by means of a securing screw 25. Adjacent the pivoted end of the brake member 20, there is provided an offset portion 20a which terminates in an upstanding flange 26 on the outer face of which there is secured a brake shoe 27 in an appropriate position to engage a surface of the adja cent trackway. The outermost end of the brake member 20 is retained and guided in its swinging movement over the adjacent surface of the frame plate 13 by means of a screw 28 provided with a large head which forms a peripheral flange 29 adapted to overlie an end portion of the brake member. From the foregoing description, it will be apparent that the spring 23 will normally urge the brake member in a clockwise direction about its screw pivot 21 to bring the brake shoe 27 into frictional braking engagement with the associated trackway structure so that the carriage will be effectively held against movement along the beam member 12 and thus support the drafting head assembly in a fixed position on the beam member.

For controlling the position of the brake member and selectively determining whether it occupies a braking or non-braking position with respect to the trackway, there is provided a unique brake actuating means which utilizes a single control member which in this case consists of an elongate actuator lever as generally indicated at 30. This lever is formed at its innermost end with an enlarged head portion 30a which is pivotally supported on the frame plate 13 by means of a pivot screw 31. The outermost end of the actuator lever is desirably formed to provide a finger grip portion 30b to permit convenient manual swinging movement of the actuator lever to the selective brake actuating and control positions as will hereinafter be more specifically described.

As shown in FIG. 1, the actuator lever 30 projects outwardly of the beam member 12 in close proximity to and above the drafting head assembly 17. The actuator lever is thus easily accessible and is arranged to be selectively positioned in three dwell positions as indicated at L1, L2 and L3. These three positions determine the operative relationship between a generally arcuate camming peripheral surface as generally indicated at 32, formed on the head portion 30a of the actuator lever, with respect to an associated follower projection 33 carried by the brake member 20.

As best shown in the enlarged view in FIG. 3, the camming peripheral surface 32 is provided with a camming lobe 34 which presents an arcuate camming surface 35 which extends from a dwell notch 36 in opposite directions to spaced dwell points defined by notches 37 and 38 respectively. The dwell notch 36 is positioned at a greater radial distance from the axis of the pivot screw 31 than the radius of notches 37 and 38. As a consequence, when the follower 33 is positioned in the notch 36, the brake member 20 will be moved in a counter-clockwise direction about its pivot 21 against the force of spring 23 to a position in which the brake shoe 27 will be in non-braking relation with respect to the trackway. When the follower projection 33 is positioned in either of the notches 37 or 38, the brake member 20 will be released to move in a clockwise position under the force of spring 23 into a braking position of the brake shoe 27 with respect to the trackway. The camming surface 32 also includes an inclined ramp portion 39 which presents a camming face 40 which extends outwardly from the notch 37 with continuously increasing radius. A stop abutment 41 at the outer end of the ramp portion 39 limits clockwise rotation of the actuator lever, while a stop abutment 42 at the notch 38 limits counter-clockwise rotation of the actuator lever. v

From the foregoing description of the braking device of the present invention, it will be apparent that the location of the actuator lever 30 is such as to permit its movement into the plurality of selective operating positions by the draftsman with an ease and convenience which is not to be found in the prior art devices. The stable dwell position L1, as shown in phantom lines in FIG. 1, will comprise the normal mode of operation. In this position, the braking mechanism will be in a braking position and the brake shoe 27 forceably urged by the spring 23 into frictional engagement with the associated trackway. In this position, the follower projection 33 will be seated in the dwell notch 37 as clearly shown in the enlarged view of FIG. 3. In this position, the spring 23 forceably urges the follower into the notch and resiliently opposes rotative movement of the actuator lever 30 in either a clockwise or counterclockwise direction. In this position of the actuator lever, the carriage and associated drafting head assembly will be firmly fixed with respect to the beam member 12. When, however, the draftsman wishes to move or shift the position of the drafting head assembly longitudinally of the beam 12, it is only necessary for the draftsman to extend one or two fingers of the hand which is on the control handle 18 so as to conveniently engage the grip portion 30b of the actuator and pull it in a clockwise direction towards the drafting head assembly; As a result of this action, the follower projection 33 will ride up the camming face 40 and move the brake member 20 in a counter-clockwise direction so as to carry the brake shoe 27 out of engagement with the associated trackway. With the carriage .thus released with respect to the beam trackways, the desired adjustment of the drafting head assembly may be made. Upon releasing the actuator lever 30, the spring 23 acting through the follower projection 33 on the camming face 40 will return the follower projection to the notch 37 and a position wherein the actuator lever will be again normally positioned as shown in phantom lines and indicated at Ll.

In the event that the draftsman wishes to have the braking device released for a longer than momentary period of time to permit unimpeded movements of the drafting head assembly along the beam member 12, the actuator lever 30 is moved to the phantom line position as indicated in FIG. 1 at L2. In this position, the follower projection 33 will be disposed in the dwell notch 36 of the lobe 34. Movement of the follower projection 33 from the notch 37 to notch 36 causes a counterclockwise rotation of the brake member 20 about its pivot 21 and movement of the brake shoe 27 to a nonbraking position.

When shipping the drafting machine, .the hinge joint 16 and associated drafting head assembly 17 would be disassembled from the beam 12 and the carriage mounted thereon. It will be appreciated that during shipping, it is desirable to have the braking device in braking position in order to prevent motion of the carriage along the trackway. At the same time it is desirable that the actuator lever should be as closely disposed along the beam 12 as possible so as to protect it against possible damage. This requirement is fulfilled in the present invention by the provision of an arrangement which permits the actuator lever 30 to be positioned as shown in full lines in FIG. 1 and indicated at L3. In this position, the lever makes a relatively small angle with respect to the beam 12 and in this position extends generally alongside the beam in such close proximity as to materially reduce the possibility of damage. Moreover, with reference to FIG. 3, the follower projection 33 would be disposed in the dwell notch 38 as the result of a camming actuation which again places the brake shoe 27 in a braking position with respect to the associated trackway.

From the foregoing description and drawings, it will be clearly evident that the delineated objects and features of the herein described invention will be accomplished.

Various modifications may suggest themselves to those skilled in the art without departing from the spirit of our invention, and, hence, we do not wish to be restricted to the specific forms shown or uses mentioned, except to the extent indicated.

We claim:

1. A braking device for a drafting machine, comprising:

a. a carriage supported for movement along a trackway;

b. a brake element carried by said carriage and supported for movement into braking and non-braking positions with respect to said trackway;

0. means normally urging said brake element towards said braking position; and

d. brake actuator means on said carriage manually operable to selectively position said brake element in a braking position and in a non-braking position, said actuator means including a generally arcuate surface portion having camming relation with a follower part connected with said brake element, and said surface having spaced dwell positions for said follower which respectively correspond to a braking position of said brake element.

2. A braking device according to claim 1, wherein said surface has another dwell position for said follower intermediate said spaced dwell positions, and which corresponds with a non-braking position of said brake element.

3. A braking device according to claim 1, wherein said surface includes an inclined ramp portion extending beyond one of said dwell positions, for coaction with said, follower to temporarily move said brake element to a non-braking position, and upon release of said actuator, return the follower to said one of said dwell positions.

4. A braking device for a drafting machine, comprising:

a. a carriage supported for movement along a trackway;

b. a brake element carried by said carriage and supported for movement into braking and non-braking positions with respect to said trackway;

0. means normally urging said brake element towards said braking position; and

d. brake actuator means on said carriage manually operable to selectively position said brake element in a braking position and in a non-braking position, said actuator means including a manually operable lever having a head end portion pivoted on said carriage, said head portion having a generally arcuate camming peripheral surface operatively associated with a cam follower part on said brake element, said surface having one section which decreases from a maximum radius point in opposite directions to spaced points respectively having a lesser radius, and an inclined ramp section extending in an opposite direction away from one of said points of lesser radius.

5. A braking device according to claim 4, wherein stops are positioned adjacent said points of lesser radius for respectively limiting rotational pivotal movements in opposite directions of said head portion.

6. A braking device for a drafting machine, comprisa. a carriage support for a drafting head assembly,

movable on a linear axis'as a unit along one side of a carriage trackway;

b. a brake element carried by said carriage and supported for movement into braking and non-braking positions with respect to said trackway;

0. means normally urging said brake element towards,

said braking position;

d. brake actuator means on said carriage including an elongated lever having an inner end pivoted on said carriage for swinging movement, and an outer end juxtaposed above said head assembly in a normal tion in which said lever extends generally along and in relatively close proximity to said trackway, and dwell means for releasably retaining said lever in said third position whereby said lever will be protected during shipment of a disassembled trackway with the carriage mounted thereon. 

1. A braking device for a drafting machine, comprising: a. a carriage supported for movement along a trackway; b. a brake element carried by said carriage and supported for movement into braking and non-braking positions with respect to said trackway; c. means normally urging said brake element towards said braking position; and d. brake actuator means on said carriage manually operable to selectively position said brake element in a braking position and in a non-braking position, said actuator means including a generally arcuate surface portion having camming relation with a follower part connected with said brake element, and said surface having spaced dwell positions for said follower which respectively correspond to a braking position of said brake element.
 2. A braking device according to claim 1, wherein said surface has another dwell position for said follower intermediate said spaced dwell positions, and which corresponds with a non-braking position of said brake element.
 3. A braking device according to claim 1, wherein said surface includes an inclined ramp portion extending beyond one of said dwell positions, for coaction with said follower to temporarily move said brake element to a non-braking position, and upon release of said actuator, return the follower to said one of said dwell positions.
 4. A braking device for a drafting machine, comprising: a. a carriage supported for movement along a trackway; b. a brake element carried by said carriage and supported for movement into braking and non-braking positions with respect to said trackway; c. means normally urging said brake element towards said braking position; and d. brake actuator means on said carriage manually operable to selectively position said brake element in a braking position and in a non-braking position, said actuator means including a manually operable lever having a head end portion pivoted on said carriage, said head portion having a generally arcuate camming peripheral surface operatively associated with a cam follower part on said brake element, said surface having one section which decreases from a maximum radius point in opposite directions to Spaced points respectively having a lesser radius, and an inclined ramp section extending in an opposite direction away from one of said points of lesser radius.
 5. A braking device according to claim 4, wherein stops are positioned adjacent said points of lesser radius for respectively limiting rotational pivotal movements in opposite directions of said head portion.
 6. A braking device for a drafting machine, comprising: a. a carriage support for a drafting head assembly, movable on a linear axis as a unit along one side of a carriage trackway; b. a brake element carried by said carriage and supported for movement into braking and non-braking positions with respect to said trackway; c. means normally urging said brake element towards said braking position; d. brake actuator means on said carriage including an elongated lever having an inner end pivoted on said carriage for swinging movement, and an outer end juxtaposed above said head assembly in a normal braking first position from which it is manually swingable away from said head assembly into a temporary non-braking position; and e. means resiliently urging said lever, upon release, in a return direction to said normal braking position.
 7. A braking device according to claim 6, wherein said lever is also movable from said normal first position in a direction away from said head assembly to a second position in which said brake element assumes a non-braking position, and dwell means for releasably retaining said lever in said second position.
 8. A braking device according to claim 7, wherein further movement of the lever in a direction away from said head assembly carries it to a full braking third position in which said lever extends generally along and in relatively close proximity to said trackway, and dwell means for releasably retaining said lever in said third position whereby said lever will be protected during shipment of a disassembled trackway with the carriage mounted thereon. 